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ATRIAL FIBRILLATION
Rhythm vs. Rate Control
Consequences of Atrial Fibrillation
Hemodynamic
loss of synchronous atrial mechanical activity
irregularity of ventricular response
inappropriately rapid heart rate
Myocardial – persistently rapid rate can lead to:
atrial cardiomyopathy
dilated ventricular cardiomyopathy
Thromboembolism
ischemic stroke and systemic arterial occlusion attributed to LA
and LAA thrombus
Up to 25% of atrial fibrillation-associated strokes may be due to
1) intrinsic cerebrovascular disease
2) other cardiac sources of embolism
3) atheromatous pathology in the proximal aorta
AFFIRM TRIAL
1) > 4000 patients randomized to rhythm vs. rate
control
> 65 years of age
medical therapy to restore rhythm or control
rate
2) Primary endpoint – total mortality at an
average of 3.5 years:
306 deaths in rate control arm
356 deaths in rhythm control arm
3) Secondary endpoint – ischemic stroke same
for both groups
RACE STUDY
(Rate Control vs. Electrical Cardioversion)
522 Patients
256 patients – rate control
266 patients – cardioversion
Outcome
Rate
Rhythm
Death/Stroke
17.2%
22.6%
Mortality
7%
6.7%
CHF
3.5%
3.4%
Hypertension Subgroup: Combined Endpoints:
Mortality/thromboembolism/severe complication
Rate
Rhythm
19%
31%
CARDIOVERSION
Predictors of success:
Short duration of atrial fibrillation
Presence of atrial flutter
Younger age
Predictors of failure:
LA enlargement
Structural heart disease
Cardiomegaly
ATRIAL FIBRILLATION
Anticoagulation Strategies
Prevalence of Atrial Fibrillation
2002: 2-3 million adults
2050: 5-6 million adults
Ischemic Stroke Risk
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Non-rheumatic atrial fibrillation: 5%/year
1/6 strokes occur in patients with atrial
fibrillation
Stroke risk in atrial fibrillation is 2 times greater
than in patients without atrial fibrillation
Only 15-44% of patients who would benefit from
prophylactic anticoagulation therapy receive
treatment
Summary
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Atrial fibrillation is the most prevalent cardiac
arrhythmia with substantial increase in cases expected
over the next 3 decades.
Atrial fibrillation is associated with >5 times increase
in stroke compared with age matched controls.
Anticoagulation with warfarin has consistently been
shown to reduce the ischemic stroke risk compared
with placebo.
Intracranial hemorrhage risk is both age and INR
dependent so patient therapy should be based upon
careful risk and benefit consideration.